Fosi Audio Box X2 Phono Preamp, Mini Stereo Audio Hi-Fi Preamplifier with Gain Gear, Pre-Amplifier for MM Turntable Phonograph and Record Player, with DC 12V Power Supply

Price: $69.99

(as of Feb 18, 2026 02:50:50 UTC –

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Product description

The video showcases the product in use.The video guides you through product setup.The video compares multiple products.The video shows the product being unpacked. Fosi Audio Box X2 Phono Preamp Merchant Video

Tube MM Phono Preamplifier/Tube Preamp

With RCA and 3.5mm AUX inputs, the BOX X2 offers flexibility to connect with various audio sources, making it a versatile addition to different systems.

Power Adapter: 12V/1.5A; Adapter Input Voltage Range: AC 110V – 240VOutput Voltage Level: 600 Mv @3mV 1kHzFrequency Response: Standard RIAA; SNR ≥ 98dB; THD ≤ 0.1%Output Impedance: 280Ω; Size: 4.66 x 3.85 x 1.29 inches; Weight: 10.9 ounces.

Clear Sound with Low Noise Circuitry

Enjoy clear and detailed sound with advanced low-noise design, delivering an authentic experience.

4-Level Gain Adjustment for Any Setup

Adjust sound with 4 gain settings for precise customization on any amplifier or speaker setup.

Minimalist Design for Any Space

The BOX X2’s sleek and compact form easily fits into any audio setup, offering style and function.

Replaceable Vacuum Tubes for Unique Tones

Achieve warm, vintage sound or modern, clear tones by replacing vacuum tubes for personalized audio.

1 Superior Audio Quality

2 Adjustable Gain Control

3 Sleek and Compact

4 Customizable Sound

Perfect Addition to Your Vinyl Setup

Turn your home into a sound haven with BOX X2, enhancing the sound of your vinyl collection.

Compatible with most MM phono turntables

Easily connects to MM phono turntables, offering a variety of choices for vinyl equipment.

3.5mm AUX Input for Easy Connections

Easily connect your phone, tablet, or other devices via the 3.5mm AUX input for more audio options.

Enhance Focus with Clear, Crisp Sound

Enjoy better audio quality in your workspace, helping you focus on tasks or relax with music.

1 Home Audio Upgrade

2 For Turntables

3 Desktop Audio Setup

4 Work in Harmony

Product Advantages RCA for MM Turntable Preamp

Ideal for MM cartridges, this mini preamp features precise RIAA equalization and low noise. It includes stereo RCA inputs and outputs.

AUX for Tube Preamplifier

Audiophile-grade amplification with low-noise operational preamps, plus a tube preamp and 3.5mm AUX input. Crafted from high-quality components.

Elegant Vacuum Tube Design

The visible vacuum tubes give a retro aesthetic while offering enhanced sound quality.

Circuit Board Layout

The circuitry is meticulously arranged to minimize interference and maximize sound quality.

My turntable has a built-in phono preamp. How do I connect it to the BOX X2?

• If the turntable has a built-in phono preamp, switch it to “Line Out” mode and connect it to the 3.5mm input on the BOX X2.

• If the turntable is set to “Phono” mode, connect it to the MM input on the BOX X2 for optimal sound.

Does the BOX X2 have any built-in tone control? Dose the BOX X2 have bluetooth?

No. The BOX X2 don’t have bluetooth. And the BOX X2 features gain control, not tone control. For enhanced tonal shaping, consider using models like BOX X4, which includes treble and bass adjustments. For bluetooth consider using models like BOX X3.

How to connect a turntable to the BOX X2 and active speakers?

Make sure the turntable has a Phono output with an MM cartridge. Some turntables have a built-in phono preamplifier, set it to Phono switch.

Can I replace the tubes in the BOX X2?

You can substitute with 7-pin tubes such as 6AK5, 6AK5W, 6Zh1P, 6J1, and 6J1P. These can also directly replace WE-403A, WE-403B, EF95, 6A2 tubes, 5725w tubes and standard 5654 tubes.

Turntable has built-in preamp/line switch—Can I still use this instead of my built-in preamp?

Yes, deselect the preamp on your turntable.

Note: Please confirm whether your turntable has a built-in phono preamp, if there is a phono preamp, and it cannot be deselected, then you can only connect 3.5 mm input, can not connect MM Turntable input.

Friendly Solutions Guide for BOX X2 Phono Preamp

I. Compatibility Limitations

1. Compatibility: The BOX X2 Output Impedance: 280Ω. Power adapter: 12V/1.5A; adapter input voltage range: AC 110V – 240V. Please use a matched power adapter and an amplifier with matched impedance to avoid incompatibility.(Does not support MC turntable)

2. Connections: The BOX X2 with RCA and 3.5mm AUX inputs. Please make sure that your turntable is MM output and also make sure that it is phono output, this situation the MM turntable can only insert RCA input. If the turntables built-in phono preamplifier, so it should connect the 3.5mm AUX input on the BOX X2 not the RCA phono input. The other device(e.g. Laptop, PC, Phone, Tablet, TV, DVD, etc.) can only insert 3.5mm AUX input. Not support Bluetooth, can connect to a pair of active speakers, but need to add an amplifier or receiver to the passive speakers.

3. For details on how to use the BOX X2 with a record player that has a built-in phono amplifier. If the turntable has a built-in phono preamp, switch it to “Line Out” mode and connect it to the 3.5mm input on the BOX X2. If the turntable is set to “Phono” mode, connect it to the MM input on the BOX X2 for optimal sound.

Note: The 3.5mm port on the front of the BOX X2 is an AUX input port and cannot be used to connect headphones.

II. Function & Sound Quality- Related Solutions

1. Cable Issues: Ensure all plugs (e.g., 3.5mm AUX Input, MM Turntable input, RCA output) are fully inserted and match the device specifications. Reseat any loose connections. Ensure all cables are correctly connected, secure, and in good condition.

2. Tube Installation: Make sure the tube pins are properly lined up with the tube socket; Please manually straighten the pins if the pin is deformed.

3. Gain Setting: 4-levels of output level setting (OFF/39/42/45 dB). Offers gain adjustment, allowing you to control the amplification level of the input signal, rather than directly controlling the volume level. The higher the gain is set, the greater the likelihood of distortion. It is recommended to prioritize adjusting the volume control knob on the speaker.

Please know that when no inputs connected to BOX X2, the default input way is MM input mode, in this mode, the gain of the amplify is much large then other input modes, so it’s normal that will have some humming sound when no sound pass through.

Tube MM Phono Preamplifier: This Fosi Audio phono preamplifier removes low-frequency noise and ensures clear sound quality by converting phono signals to line-level signals using high-quality components and low-noise integrated circuits. It is designed to safeguard your turntable thanks to its grounding post
3 Switchable Gain Modes: You can switch between 3 modes: 39, 42, or 45 dB. High compatibility and customizable control are provided by the adjustable gain levels. Also, it has very good circuitry and entry-level, high-end analog sound
Tube Preamplifier: With a 3.5mm AUX input, it’s also a tube preamp. Fosi Audio used high-quality component parts for the design and assemblage of this phono preamplifier. You can enjoy a very warm and smooth sound
Applicable Vacuum Tube Model: The compatible vacuum tube models are 6K4, 6J1, 6J4, GE5654, 6AK5, 66, etc. To make changes to your stereo system yourself, simply swap out the vacuum tubes. Consider that distinct tubes produce various sounds
Package Content: You will get 1 x Box X2 phono preamp, 2 x vacuum tubes, 1 x RCA cable, 1 x power adaptor, and 1 x user manual